People suffering from diabetes have abnormally high levels of blood sugar or blood glucose because of inadequate production of insulin by the body or the body's incapability of properly responding to the present insulin.
Diabetes is generally considered incurable and regular monitoring and controlling of blood sugar level is a major part of the treatment. Patients with diabetes control their blood sugar levels through medication, diet and exercise, and in some cases insulin injections. Patients often need to monitor their own blood sugar levels at home on a daily basis to ensure effectiveness of the treatment regime.
Today's technology allows blood tests to be performed by patients at home using a portable test kit commonly called a glucose meter. To use the meter, a patient draws a blood sample by using a lancing device to prick a finger, applies the blood on a test strip inserted into the glucose meter. The glucose meter automatically performs analysis on the blood on the test strip and shows the glucose level readout in a display panel on the meter.
Because the lancing devices and test strips for a glucose meter are typically designed as disposable, the expense of using such a glucose meter can be a substantial economic burden. For instance, some patients need to test up to 5 times a day and thus use at least 5 lancets and 5 test strips, which can cost $600-1500 per year for each individual depending on the prices of the test strips and lancets. Besides the economic waste, disposable lancing devices and test strips are also a significant source of medical waste hazards and contribute to environmental contamination. In addition, pricking fingers or alternative sites to draw blood samples inflict physical discomfort and pain. Patients often feel the testing processes unpleasant and burdensome.
There have been recent developments in using non-invasive approaches to monitor and test glucose levels in patients. Studies have shown that human tear liquid also contains glucose, albeit in a diluted concentration compared to the blood. Human eyes are constantly lubricated and covered by a tear layer, and an elevated blood glucose level results in an elevated tear glucose level. Thus, instead of directly testing glucose contained in blood samples, there has been reported research in using contact lens built with on-lens electrochemical sensors and integrated circuitry to test glucose levels in tear liquid.
While this approach transforms the blood glucose test to a non-invasive nature, it requires patients to wear contact lens, which is still considered inconvenient and cumbersome to many patients.